San Luis Potosí → Guanajuato · Autopista 57D México-San Luis Potosí
The night-time return from San Luis Potosí, San Luis Potosí, to Celaya, Guanajuato, deserves its own protocol: anti-glare driving glasses on, dashboard light dimmed to the lowest setting, and well-lit truck stops pre-identified as candidate rest stops. The 228 km (142 miles) of Autopista 57D México-San Luis Potosí and the 2h 32m of driving cross zones with patchy cellular coverage during the small hours. Approximate refuel cost on the way back stays at MXN 459.80 for the 19 liters (5.0 gallons) consumed. Forecast reimbursement for the night leg holds at MXN 1482.00 applying the prevailing MXN 6.50/km — without an automatic night premium in the tarifa promedio de mercado table. If the company pays night-driving overtime, open a separate line on the Clara receipt: the payroll integration already recognizes the entry. For the US professional driving the 228 km (142 mi) between San Luis Potosí and Celaya, reimbursement of MXN 1482.00 stays non-taxable to the employee when the employer follows an accountable plan under Treas. Reg. §1.62-2 and reimburses at or below the IRS standard mileage rate. US employers generally reimburse at the IRS standard mileage rate so the payment stays non-taxable to the employee under Pub. 463. Keep the IRS-compliant expense report (Form 1040 Schedule C, line 9) alongside the fuel receipt from any EIA-tracked retail station network pump used along the leg; Internal Revenue Service (IRS) examiners pull contemporaneous mileage logs first when auditing Schedule C unreimbursed business expenses, and the San Luis Potosí→Celaya corridor must show date, business purpose, and odometer readings.