France’s higher borrowing costs arrive one maturity at a time

On 15 October 2026, France auctioned a zero-coupon bond at a weighted average yield of 4.10%. The security matures on 25 November 2031. Its weighted average issue price, €81.45 for every €100 due at redemption, tells us considerably more about the Treasury’s financing conditions than the zero in its name. S03 S04

That transaction offers a useful starting point for understanding France’s rising debt bill. Existing bonds retain their contractual payments; new borrowing takes place at the price investors are prepared to pay today. The effect on public finances then depends on which securities mature, how much additional funding is required and when the cost is recognised. A maturity schedule can spread the impact over years, allowing expenditure to keep rising even after market yields have started to fall.

Our reconstruction identifies €165.642 billion of conventional fixed-rate government bonds maturing in 2027. Refinancing that frozen sample at par with a 4% coupon would raise its annual coupon payments from €2.812 billion to €6.626 billion. The €3.814 billion difference is the annual rate of additional payments reached after the final rollover. Allocating it only to the days remaining in 2027 after each maturity produces €2.189 billion. This deliberately limited coupon exercise explains the lag; it does not forecast the budget’s cash payments. S07 M1

The price behind the zero coupon

The 15 October auction allocated €2.337 billion of face value in the November 2031 zero-coupon bond. At the published average price, the Treasury is due to receive approximately €1.903 billion on the scheduled settlement date of 19 October. It must repay €2.337 billion at maturity. The difference is about €433.5 million over the security’s remaining life. Settlement is still in the future as this article is written, and the calculation covers the announced competitive auction allocation. S03 M1

A bond coupon is a periodic payment specified by the bond contract. Yield relates the whole stream of future payments to the actual purchase price, allowing for time. An investor can therefore accept no coupon when the eventual redemption payment is sufficiently larger than the initial outlay. The €18.55 difference per €100 of face value is not an annual interest rate. It builds up over the bond’s remaining lifetime. S04 S11

Agence France Trésor, the French debt management office, can reopen an existing bond by issuing more securities with the same terms. Those securities share a coupon and redemption date, but each auction takes place at current market prices. An earlier holder keeps the same claim; a new buyer pays a different price for identical future payments. A large outstanding issue can support trading liquidity, while the issue discount brings the new buyer’s yield into line with market conditions. S11

Choosing a low coupon consequently provides no free saving. Under comparable market conditions, the government receives less cash when it issues the bond and may have to create more face-value debt to raise a given amount of money. National accounts and the government’s accrual accounts spread issue premiums and discounts over the life of the security. Cash financing and the budgetary treatment of coupons follow different rules. The timing of the reported cost changes, but the economic commitment remains. S11 S12

An eight-year average and near-term funding needs

At 30 September 2026, France’s marketable state debt amounted to €2,896.181 billion, with an average remaining life of eight years and 158 days. That is the portfolio managed by AFT. It is a different perimeter from general government debt, which also includes liabilities of local authorities and social security bodies. S02

The long average maturity provides genuine protection: coupons on outstanding conventional fixed-rate bonds do not reset whenever market prices move. An average, however, tells us where maturities lie in aggregate. It does not mean refinancing begins eight years from now, or that precisely one eighth of the debt is renewed each year. A portfolio can combine substantial short-term funding with a small number of very long bonds and still display a reassuring average.

French Treasury bills, known as BTFs, are the faster transmission channel. Their outstanding amount was €217.658 billion at the same date, equivalent to 7.5% of marketable state debt, and their average remaining life was 129 days. As bills expire, replacement funding can quickly pick up new market conditions. Even with an unchanged outstanding stock, the Treasury may issue a large volume of bills repeatedly during the year. S02 M1

On an unchanged bill stock, a one-percentage-point increase in the borrowing rate would amount to approximately €2.18 billion a year once the entire stock had rolled over at the higher rate. That is an annualised sensitivity, with no assumption about when the shock occurs or the prices of future auctions. It cannot be treated as a certain addition to expenditure in the first year. M1

Long-dated bonds transmit changes more slowly, but involve much larger principal amounts. Inflation-linked securities add a separate channel: the principal grows with the reference price index, without requiring any new borrowing. The budget responds to refinancing dates, new borrowing and inflation indexation through distinct contractual mechanisms. S09 S10

The bonds leaving the portfolio in 2027

To make the transition tangible, we extracted the securities maturing in 2027 from AFT’s September bulletin. The table records settled outstanding amounts at 31 August 2026. It is a dated snapshot, rather than a definitive forecast of next year’s redemptions. Four conventional fixed-rate OATs account for €165.642 billion, with coupons ranging from zero to 2.75%. OAT is the French designation for these government bonds. S07

The February maturity contains €35.818 billion with a zero coupon. May brings €38.944 billion at 1%. The two autumn maturities hold €30.797 billion at 2.50% and €60.083 billion at 2.75%. Timing matters alongside size: a bond refinanced in February starts accumulating interest at its new terms much earlier in the year than a bond replaced in October. S07

A fifth security, due in July, is linked to euro-area inflation. Its €21.737 billion face value had already become €30.598 billion after applying the end-August indexation coefficient. Its 1.85% coupon is a real coupon applied to inflation-adjusted principal. Comparing it directly with a 4% nominal borrowing rate would leave inflation out of the calculation. We therefore exclude it from the conventional-bond rollover exercise. S07 S10 S14

The snapshot is useful because the contracts and their dates can be inspected. It is not a promise that the portfolio will remain unchanged. AFT may buy bonds back before maturity, reopen issues or alter its cash position. The five lines’ combined outstanding amount, including indexation at 31 August, should not be forced to match the draft budget’s redemption forecast, which uses a different information set and assumptions about debt management. S05 S06 S07

The annual payment rate rises in steps

The exercise replaces each of the four conventional bonds at maturity with a new bond issued at par for the same face value. We test new coupons of 3%, 4% and 5%, held constant within each scenario. Issuance at par means receiving €100 for €100 of principal, so the coupon equals the initial yield. The replacement bonds are assumed to remain outstanding beyond 2028. M1

Our benchmark is a hypothetical continuation of the old coupons on the same principal after the original maturity dates. It answers a narrow question: what annual pattern of periodic payments would replace the inherited contracts? It does not reconstruct the historical effective borrowing cost of those bonds, some of which were themselves issued at a premium or a discount. The zero-coupon example makes it particularly important to retain that distinction.

At 4%, the replacement bonds would pay €6.626 billion of annual coupons, compared with €2.812 billion on the old sample. The whole portfolio does not change on 1 January, however. February’s refinancing adds €1.433 billion to the annual payment rate. May’s takes the combined increase to €2.601 billion. The two remaining maturities lift it to €3.063 billion and then €3.814 billion. M1

The area under that staircase measures the additional coupons allocated over time: approximately €2.189 billion between the individual refinancing dates and the end of 2027. We use actual calendar days and a 365-day year. The €3.814 billion figure is an annual rate reached at year-end; €2.189 billion is the amount attributed to the portions of 2027 after each replacement. They are different measures and cannot sensibly be added together. M1

There is one more step before cash leaves the Treasury. If each replacement bond pays its first coupon one year after issue, the first cash payment falls in 2028. Reopening an existing bond with a different coupon date and accrued interest at issue gives a different cash schedule. Our time-allocation measure does not model those payment calendars. Nor should it be added to the draft 2027 budget, whose projections already include financing assumptions, or presented as an alternative forecast of its debt-service appropriation. M1 S11

The most revealing result comes from the 3% scenario. Even at that rate, below those in the auction discussed here, replacement bonds would carry approximately €2.158 billion more in annual coupons than the old sample. Applying the same time convention allocates €1.454 billion of that increase to 2027. Better terms on new borrowing can therefore coexist with a rising coupon bill when the contracts being retired carried lower coupons. S03 M1

This inertia works in both directions. Inherited low fixed coupons initially slow the increase in contractual payments. Once bonds have been refinanced more expensively, the resulting fixed contracts delay the benefit of a subsequent decline in market rates. The rollover schedule turns a market movement into a sequence of commitments lasting well beyond the original shock. This refinancing risk depends on the amounts due and the terms available when each maturity arrives.

New borrowing adds to refinancing

Replacing maturing debt does not cover all of the Treasury’s work. The draft 2027 budget provides for €340 billion of medium- and long-term issuance, net of buybacks. On the same face-value basis, principal redemptions account for €179.5 billion. The €160.5 billion difference is the projected net increase in marketable state debt with a maturity above one year. S06

The word “net” matters. Here it deducts early buybacks from issuance, not redemptions at contractual maturity. Describing the entire €340 billion as additional debt would overstate growth in the stock. Describing it entirely as the replacement of old borrowing would erase the government’s additional financing needs. S06

The projected cash financing requirement is €339.7 billion. It includes a €156.4 billion budget deficit, principal repayments and other adjustments. Interest expenditure is already inside the budget deficit: adding it again would manufacture a financing requirement that does not exist. The numerical proximity of €339.7 billion in cash needs and €340 billion in bond issuance does not make them the same concept. S06

The zero-coupon auction shows why. Issuing €100 of debt at the auction’s average price raises only €81.45 in cash. Across the 2027 programme, the financing table assumes a negative €8 billion contribution from net issue premiums and discounts. That is a cash-financing assumption associated with issue prices, rather than a line of coupons paid during the year. S03 S06 S11

Additional borrowing exposes a fresh portion of the balance sheet to prevailing rates without waiting for an older bond to expire. A well-spread redemption profile consequently offers only partial protection when the outstanding debt continues to grow. The annual flow of funding needs must be considered alongside the maturity of the existing stock.

Inflation follows a separate timetable

With an inflation-linked bond, the redemption commitment increases with the reference price index. The budget records an annual provision for that indexation, while the additional principal is paid when the bond matures. Budgetary expenditure can therefore arise before the principal is paid. Annual coupons also change as the fixed real coupon rate applies to inflation-adjusted principal at each coupon date. S09 S10 S12

The draft 2027 budget makes the distinction visible. It includes €8.5 billion of annual indexation provision, removed in the conversion from the budget deficit to cash financing needs because it is not immediately paid out. It also includes €9.7 billion of indexation supplements paid at redemption. The first concerns the charge recognised for the year; the second concerns accumulated revaluation attached to the securities being repaid. S06

Subtracting those amounts and calling the difference an inflation saving would compare unlike measures. Adding them without examining their treatment would be equally misleading. Removing the provision from the cash bridge prevents a non-cash budget entry from becoming a fictitious immediate financing need. Paying the accumulated indexation on maturing securities does require funds. S06 S12

This complicates the familiar claim that inflation automatically makes government debt easier to bear. Inflation may raise nominal GDP and some tax receipts, improving particular ratios, while directly increasing indexed liabilities. The net outcome depends on the debt mix, the response of revenue and expenditure and the yields demanded on subsequent issuance. No single channel establishes an overall benefit to the public finances.

Market prices and contractual payments

A rise in yields reduces the market value of an existing fixed-rate bond, producing a valuation loss for its holder. The Treasury retains the contractual payment schedule. A lower secondary-market price does not automatically reduce the principal due at redemption. S04 S11

The state can buy a security back early, but that requires cash and must be assessed alongside the funding used to obtain it. Replacing a discounted old bond with a new loan at a higher yield does not, by itself, create an economic saving equal to the discount. The comparison needs to include future payments and their present value. S11

This timing difference explains how market-price stress can precede a rise in government expenditure. Investors facing valuation losses may seek to reduce their positions before the Treasury has paid more interest. That is a plausible risk channel, rather than evidence of forced sales in this investigation. Our evidence does not measure margin calls or the positions of bondholders, and cannot diagnose a liquidity crisis from the ten-year yield alone.

Persistent yields complicate fiscal adjustment

AFT’s daily TEC 10 indicator stood at 4.79% on 16 October. It represents a constant ten-year maturity, not the yield of every auction or the effective rate applied to the entire debt stock. A Reuters interview published that day reported the IMF’s assessment that France retains short-term buffers, while persistently high borrowing costs would make fiscal adjustment harder. S01 S13

Issuance data provide a concrete counterweight to immediate funding-stop scenarios. AFT said that 85% of its annual programme had been completed by the end of September. The 15 October zero-coupon auction had a bid-to-cover ratio of 2.30. Investors accepted that allocation at the prices established in the auction. A coverage ratio offers no guarantee about future funding conditions; it describes the bids submitted in a particular operation. S03 S05

The material fiscal risk is a succession of more expensive rollovers, potentially combined with larger additional borrowing needs. Gradual transmission creates time to respond. It can also make a market move appear harmless until the new commitments have accumulated across several budget years.

An earlier AFT sensitivity exercise, reproduced by the Senate in November 2025, illustrates the process. A permanent one-percentage-point rise across the whole yield curve increased annual debt-service costs by €3.2 billion at a one-year horizon, €23.5 billion at five years and €33.5 billion at nine years. These are annual increases at the stated horizons, not a cumulative bill. The vintage prevents them from being presented as an October 2026 update. They illustrate the shape of transmission rather than an amount that can now be entered in next year’s budget. S08

The strongest argument against an alarmist reading remains substantial. Long maturities, the possibility of lower market yields and a reduction in additional borrowing needs all leave room to adapt. Their value depends on timing. A decline in yields before a large refinancing date has a different effect from a decline immediately after the replacement bond has locked in its cost.

Signed contracts leave a long fiscal footprint

The proposed 2027 appropriations contain €72.373 billion for state debt and cash management, plus €561 million for servicing SNCF Réseau debt assumed by the state. Together they amount to €72.934 billion, consistent with the rounded €72.9 billion announced by AFT. These are budget forecasts, not expenditure already incurred, and they do not cover all interest paid by every part of general government. S05 S06

One documentary discrepancy needs to remain visible. AFT’s budget page puts its 2026 debt-charge forecast at €62.6 billion, while the deposited budget bill describes a €9.6 billion increase between its revised 2026 baseline and 2027. Those statements do not directly reconcile with the €72.9 billion total. We found no sufficiently explicit public bridge establishing whether the difference reflects revisions or scope. We therefore retain the verified 2027 programme total without computing an overall growth rate from unreconciled baselines. S05 S06

Debt sustainability ultimately depends on the average cost actually borne, nominal economic growth and the fiscal balance before interest. As the average financing cost rises, part of an improvement in tax revenue or non-interest spending can be absorbed by commitments inherited from earlier borrowing. If fiscal adjustment also weakens activity, its effect on the debt ratio becomes less certain. An accounting relationship helps identify those pressures but cannot, on its own, predict the economy or investors’ response.

The timetable nevertheless supports a firm conclusion. Higher rates affect new transactions immediately, then work through fiscal years as old contracts are replaced and payments fall due. In the sample examined here, the February and May 2027 maturities bring that transition forward, while the autumn maturities extend its effect beyond the year. The useful question is specific: on what terms will maturing principal be replaced, and how much extra borrowing will be needed alongside it?

Method and limitations

Market observations end on 16 October 2026; the research was checked on 17 October. Security-level amounts are deliberately frozen at 31 August, the date of the AFT table used. The scenario includes only four conventional fixed-rate bonds maturing in 2027, with no subsequent reopening, buyback, short-term debt or inflation adjustment. The methods below the figures give the nominal-euro inputs, day-count conventions and calculation formulas. No probabilities are assigned to the 3%, 4% and 5% cases. They compare coupon streams under stated assumptions, without purporting to reconstruct the full effective cost of the older issues. M1

Further reading: France’s choice of maturities and rollover risk complements this security-level reconstruction. The episode on the price of exiting traces sales through market pricing and new issuance. The 2027 budget analysis and model explores other assumptions within its own scope.

Sources and calculations

Sources consulted on 17 October 2026. Observation dates are document-specific; the 2027 budget figures are draft projections.

1. [S01] Agence France Trésor. Daily TEC 10 indicator. 16 October 2026.
2. [S02] Agence France Trésor. Marketable state debt at 30 September 2026. 30 September 2026 stock.
3. [S03] Agence France Trésor. 15 October 2026 medium-term OAT auction. Auction 15 October; settlement 19 October 2026.
4. [S04] Agence France Trésor. Zero-coupon OAT due 25 November 2031, FR0014002WK3. Contractual terms; the dynamic outstanding amount is not a settled snapshot.
5. [S05] Agence France Trésor. State budget: 2027 draft and revised 2026 figures. Draft projections for 2027 and revised 2026.
6. [S06] Gouvernement / Assemblée nationale. Draft Finance Bill for 2027, no. 3210. Filed 1 October 2026; draft rather than enacted law.
7. [S07] Agence France Trésor. Monthly Bulletin 436, September 2026, p. 5. Settled stock at 31 August 2026.
8. [S08] Sénat / données AFT. 2026 budget report, state financial commitments, 24 November 2025. 2025 vintage; annual sensitivity at one-, five- and nine-year horizons.
9. [S09] Agence France Trésor. French-inflation-linked OAT terms. Contractual indexation terms.
10. [S10] Agence France Trésor. Euro-area-inflation-linked OAT terms. Euro-area HICP excluding tobacco.
11. [S11] Assemblée nationale. 2024 state accounts: issue premiums and discounts. 2024 accounts and accounting conventions.
12. [S12] Assemblée nationale. 2025 state accounts: indexation provision, 27 May 2026. Accounting mechanism; report filed 27 May 2026.
13. [S13] Reuters. Reuters interview with the IMF on French borrowing costs, 16 October 2026. Interview retrieved through Reuters syndication; attributed assessment. Reuters text republished by MarketScreener.
14. [S14] Agence France Trésor. 1.85% inflation-linked OAT due 25 July 2027, FR0011008705. Contractual terms; dated stock from S07.